Zeolite catalyst

ABSTRACT

An improved alkylation catalyst is provided exemplified by a type X or Y zeolite with cesium, rubidium or potassium cations, and with a boron or phosphorous component added. The catalyst is useful in producing styrene from toluene and methanol.

This invention relates to particular modified zeolite catalysts andtheir uses in alkylation of toluene to styrene and ethylbenzene.

BACKGROUND OF THE INVENTION

Various alumina-silicate catalysts have been known for variousalkylations of aromatic compounds, such as the X- or Y- type zeolitesdescribed in U.S. Pat. No. 3,251,897. The alkylation of toluene withmethanol in the presence of a cation exchanged zeolite has beendescribed by Yashima et al in the Journal of Catalysis, Vol 26, 303-312(1972), with styrene and ethylbenzene included in products produced.

SUMMARY OF THE INVENTION

It has now been found that certain additives result in improvement ofparticular zeolite catalysts for the production of styrene andethylbenzene in alkylation reactions. The improved zeolite catalystshave boron or phosphorous incorporated therein, with the zeolite being acrystalline aluminosilicate of the faujasite structure with SiO₂ /Al₂ O₃mole ratio in the range of about 2 to about 8, and with some portion ofthe alkali metal present being potassium, rubidium, cesium, or mixturesthereof. The zeolites utilized are exemplified by X- and Y- typezeolites, and cesium is the preferred cation, with a major amount of thesodium or other cation generally present being replaced by the cesium.The improved catalysts can be utilized in an improved process forproducing styrene and ethylbenzene by alkylation of toluene withalkylating agents such as methanol, with improved selectivity to suchproducts and/or higher ratio of styrene to ethylbenzene in the product.Procedures are provided for incorporating the boron or phosphorouscomponents.

DETAILED DESCRIPTION OF THE INVENTION

Styrene is a commodity chemical sold and utilized in extremely largevolume for producing polystyrene and other products. Hence any processfor producing styrene is of great interest if it offers a potentialadvantage in cost or in availability of reactant materials. Toluene andmethanol are potentially attractive source materials for production ofstyrene, and the present invention provides an improved process forproducing styrene from such materials. Zeolites have previously beenemployed for alkylation of toluene to styrene, but zeolites are capableof catalyzing a variety of reactions, and therefore generally produce avariety of materials along with the desired alkylation product. In thepresent invention a catalyst is provided which gives improvedselectivity to the desired styrene and ethylbenzene products, often witha high ratio of styrene in such products. The catalysts also in generalhave good activity, in many cases giving higher conversions thanpreviously known zeolite catalysts for such reactions.

In the production of styrene and ethylbenzene, the present catalysts canbe employed under conditions generally used in alkylation reactions,such as those used in methylation of toluene with other zeolitecatalysts, with the selection of particular conditions being influencedby such considerations as activity and temperature stability of theparticular catalyst, desired conversion and attainable productselectivity. Temperatures appropriate for alkylations can be used, forexample about 350° C. to about 500° C. or so, but preferred temperaturesare about 400° C. to 475° C. Higher temperatures can be used, but tendto degrade reactants, and are not necessary as high conversions can beattained in the stated ranges. The reactants can be brought into contactwith the catalyst in usual manner, generally as a stream of reactantsconducted over or through a bed of catalyst. The contact time can bevaried over a wide range, but will generally be selected to obtain anacceptable conversion per pass at the reaction temperature. For example,ranges of gas hourly space velocities from 50 to 5,000 hr⁻¹ or more areoperable, and good conversions can often be obtained even at reasonablyhigh space velocities such as 500 to 1,500 hr⁻¹ or so. The reaction ingeneral will occur as long as quantities of both methanol and tolueneare present, in ranges, for example, of 0.5 to 20 or more moles tolueneper mole methanol. However, since only one methanol molecule is needed,and to minimize side reactions, the toluene is generally used in excess,often for example, in the range of 2 to 10 or 20 or more moles tolueneper mole methanol.

Methylations of toluene can produce some methanol decompositionproducts, and over some catalysts are capable of producing variousxylenes or other alkylated aromatics, as well as some polymer,aromatization and coke materials, along with the styrene andethylbenzene sought in the process of the present invention. The presentinvention provides a means of directing the process toward production ofstyrene and ethylbenzene, and to some extent particularly towardstyrene. It is obvious that there is economic advantage in directing theprocess to desired product at the expense of waste or less desiredproduct. The use of the present improved catalysts increases theselectivity to styrene and ethylbenzene, i.e., it increases the amountof these products obtained per unit of methanol which has reacted. Also,or in some cases alternatively, it increases the amount of styrene inthe desired products, i.e., the ratio of styrene to styrene plusethylbenzene. Both styrene and ethylbenzene are useful products andsought in the present invention. However, the usual use for ethylbenzeneis to prepare styrene by dehydrogenation, and therefore styrene is themore valuable product and there is some advantage in directing theprocess toward styrene at the expense of ethylbenzene.

In the methylation process of the present invention, improved zeolitecatalysts containing phosphorus and boron components are utilized. Thosewith a boron component are preferred, exhibiting marked improvement inselectivity to styrene and ethylbenzene, as well as improvement in theratio of styrene in such products. The phosphorus component tends tohave a stronger effect upon the ratio of styrene than upon selectivity,but nevertheless provides an advantage

In methylation reactions employing the present catalyst, it is notnecessary to employ any diluents as the reactants can simply beconducted over the catalyst. A closed system is utilized, therebyavoiding possible adverse effects of air, moisture, etc. but it is notnecessary to rigidly exclude such materials by removing all traces fromthe system. Over a period of time the catalyst is subject to loss ofactivity from carbon deposition etc. and can be regenerated by heatingin air to remove the carbon.

Zeolites are known for the alkylation of toluene to styrene andethylbenzene, and in general zeolites suitable for such reaction can bemodified as taught herein to provide the improved catalysts of thepresent invention. For example, the X- or Y- type zeolites described inthe aforesaid U.S. Pat. No. 3,251,897, or the zeolites described in theaforesaid Journal of Catalysts publication, including those for whichoriginal sources are cited therein. As taught herein, the modificationwill include a cation exchange to provide potassium, rubidium, or cesiumions, if not already present, and the incorporation of boron orphosphorus into the zeolite. In general suitable zeolites will be of thefaujasite structure with an SiO₂ /Al₂ O₃ mole ratio in the range ofabout 2 to about 8. A number of zeolites having higher silica to aluminaratios, such as 12 or much higher, have recently been advanced forvarious aromatization and alkylation reactions, but in general do notappear suitable for use in the present invention. With regard tostructural classification, those zeolites with a double 6-ring orfaujasite structure are generally suitable for use herein. Such zeolitescharacteristically have pore diameters in excess of 6 angstroms, whichis appropriate for admission of methanol and toluene, and to allow exitof styrene and ethylbenzene. The X- and Y- type zeolites have been foundvery suitable for modification and use herein, with the X-type beingparticularly preferred. Type X has a typical oxide formula Na₂ O.Al₂O₃.2.5SiO₂.6H₂ O with SiO₂ /Al₂ O₃ in the range of 2.0-3.0. Type Y has atypical oxide formula Na₂ O.Al₂ O₃.4.8SiO₂.8.9H₂ O with SiO₂ /Al₂ O₃range from 3.0-6.0. Type L zeolites and natural faujasite materials areexamples of other zeolites having appropriate pore size and structurefor use herein. In general, zeolites having suitable properties can beutilized, whether obtainable as natural materials or preparedsynthetically, and can be obtained from commercial sources or preparedby appropriate laboratory crystallization procedures.

The zeolites utilized herein are modified to have potassium, rubidium orcesium ions present, individually or together. Usual ion exchangeprocedures can be employed to replace the sodium, hydrogen or other ionsof the zeolite with the desired cations. If equivalent zeolites could beprepared directly with the desired cations, the zeolites could beutilized herein, but present practice is to prepare the zeolites by ionexchange procedures. In theory, 81% of sodium on type X and 71% on typeY is exchangeable, and it will ordinarily be desirable to exchange 50%or more for potassium, rubidium or cesium. Smaller portions, for example20 or 30% or more, will have some effect and provide improved catalystsas taught herein, but the improvement is generally enhanced withincreasing percentage change, up to 60% or so. Above about 60%,improvement is not apparent, and the usual exchange procedures do notreadily produce exchanges above 65% or so or closely approach thetheoretical. For the catalysts herein, cesium is the preferred cationfor the zeolite. The boron and phosphorus additives have a desiredeffect on the rubidium and potassium exchanged materials, which in someaspects is very marked, but the cesium zeolite even without additionaladditive, is generally better, and with the additive boron or phosphorusgives superior selectivity to styrene and ethylbenzene or a better ratioof styrene, and often better activity as well. At times it may beconvenient or desirable to employ a mixture of cations, such as amixture of rubidium and cesium, and, of course the common preparationsgenerally result in a mixture of a minor amount of sodium with one ofthe other cations.

The present improved catalysts include a boron or phosphorus element orcompound. The additional component serves as a promoter to cause somereactions to be favored at the expense of others. A small amount of theboron or phosphorus is sufficient, but the effective amounts are notnarrowly critical. While extremely small amounts will have some effect,an amount sufficient to approach optimum effectiveness will preferablybe used. Excess over the optimum can be used, but large excesses willnot give any additional benefit, and may tend to cause unnecessary lossof catalyst activity because of diluent or other effect. Generally theamounts employed will not be in excess of 5% by weight of the boron orphosphorus, on an elemental basis, and usually in the range of about0.1% to about 2% by weight. The amounts have reference to the amount inthe catalyst, rather than the amounts used in the preparation, whichoften are much larger, depending upon method of preparation.

The particular form of the boron or phosphorus component has notdefinitely been ascertained, but it has been found effective andapparently boron or phosphorus components retained in the catalyst, ifnot in proper form, are converted into effective form either in thecatalyst preparation or under use conditions. Presumably boron andphosphorus are in some oxide form, and there is some evidence that theboron is actually bonded to the zeolite. Thus preparation methods areused which result in retention of the boron or phosphorus in thezeolite, and various compounds and procedures have been found suitablefor this purpose. The boron and phosphorus components can be added tothe zeolite during cation exchange procedures, or in subsequenttreatments. After the boron or phosphorus component has beenincorporated, there appears to be some potential loss by leaching orexchange, so it is generally preferred to avoid excessive washing orsimilar procedures subsequent to incorporation of the boron orphosphorus. Also it will be undesirable to subject the catalyst totreatments known to cause loss of cations by exchange with hydrogen orother ions. Moreover, the selection of solvents for exchange orimpregnation procedures has an influence on retention of the componentsin the catalyst. Solutions or slurries of boron or phosporus compoundsin such solvents as acetone, methanol, etc. can be used. Alternatively,the boron or phosphorus can be incorporated by physical admixture of theoxides or other liquid or solid compounds into the zeolite, generally inpowdered or other particulate form. Various forms of the compounds canbe used, e.g. sodium or potassium tetraborate, B₂ O₃, boric acid,tripentyl borate, trimethoxy borate, phosphoric acid and its esters,e.g. trimethoxyphosphate, K₃ PO₄, etc. Other forms of boron orphosphorus can readily be selected which can conveniently be employed toresult in incorporation of boron or phosphorus into the catalyst. Ingeneral any methods of contacting the catalyst with boron or phosphorusin a form resulting in retention in the catalyst are suitable. While thecatalyst will generally be prepared in advance of use, it is consideredfeasible to introduce boron or phosphorus into the catalyst along withalkylation process reactants, as by adding a volatile boron orphosphorus compound to the reactants and contacting the catalyst zeolitematerial therewith, or by introducing such boron or phosphorus compoundwith inert diluent prior to introduction of the reactants. Asillustrated herein, the boron or phosphorus component can convenientlybe incorporated by inclusion in an ion exchange solution, or bysubsequently utilizing a solution of such component as a slurryingmedium for catalyst particles or as an impregnating medium to beabsorbed in the catalyst. The media for incorporating the boron andphosphorus do not necessarily have to completely dissolve the boron orphosphorus material, and in fact may often contain suspended solids.

The catalyst is generally dried following impregnation or other liquidtreatment procedures, as by heating at about 100° C. for a sufficienttime, but such procedure can be omitted. The catalyst can be activatedby calcining, i.e., heating to elevated temperatures, usually as high asthe contemplated reaction-use temperature, and often higher. Activationtemperatures in the general range of 400° to 650° C. or so can be used,ordinarily in a stream of air or inert gas. It is preferred to activatein a flowing stream to mitigate possible adverse effects of water beingremoved, but this precaution is not essential to the preparation of thepresent improved catalyst. The heating will cause fusion and/ordecomposition of many boron or phosphorus compounds, thereby possiblyresulting in closer association with the zeolite.

The present catalyst is adaptable to use in the various physical formsin which catalysts are commonly used, as particulate material in acontact bed, or a coating material on monolithic structures, generallybeing used in a form to provide high surface area. The catalyst can ifdesired be composited with various catalyst binder or support materialswhich do not adversely affect the catalyst or the reactions in which thecatalyst is to be employed.

The present catalysts are well suited for use in the methylation oftoluene to styrene. However, the catalysts are also contemplated ashaving utility in various condensation type reactions. Acidic zeolitecatalysts, which have various known uses, can often be converted tobasic catalysts by ion exchange with such ions as cesium. Such basiccatalysts tend to convert methanol, apparently through an intermediate,to carbon monoxide, rather than to dimethylether. Borate modification ofthe catalyst makes it slightly less basic, but it retains selectivity tocarbon monoxide in methanol reactions. Thus the catalyst may be usefulin various reactions of methanol involving production of carbon monoxideas an intermediate. The catalyst may also find use in other reactions oftoluene involving activation such that reaction occurs at the methylgroup rather than on the ring.

The following examples are illustrative of the invention.

EXAMPLE 1

A zeolite catalyst with cesium cation and boron additive was prepared asfollows. One liter of an aqueous solution was prepared containing 75grams CsOH and 50 grams H₃ BO₃. Twenty grams of a type X zeolite (LindeSK20) was ion exchanged with a 300 ml portion of the solution withstirring at about 100° C. for 2 hours. The exchange procedure wasrepeated for 3 hours with another 300 ml. portion of the solution. Theprocedure was then repeated overnight using the remaining 400 ml.solution. The solid zeolite was then dried at 100° C. in air for 4hours. The resulting solid powder was pressed under pressure into 1 inchdisks, which were then crushed and screened into 8 × 30 mesh particles.The catalyst can then be activated by heating to about reactiontemperature, or approximately 450° C., in inert gas, such as a flowingnitrogen stream, or in air. The thus prepared catalyst is suitable formethylation of toluene, with very good selectivity to styrene andethylbenzene. In procedures utilizing 14 different samples of suchcatalyst, in reacting methanol with toluene at 410° C. to about 60%conversion of the methanol, the average selectivity to styrene plusethylbenzene was 50%, with the ratio of styrene to styrene plusethylbenzene being 38%. This compares to a selectivity of 39.7% andratio of 21% for a control catalyst having cesium in a type X zeolite,prepared by the same procedure but without the boron component.Considered on a basis of 80% conversion, the selectivity for theboron-containing catalyst is 48.4%, compared to 35.2% for the controlcatalyst.

EXAMPLE 2

Catalyst samples were prepared by an ion exchange procedure as describedin Example 1, but without boric acid in the exchange solution. Boricacid was then added to the catalyst by slurrying the cesium zeoliteobtained from 20 grams of zeolite X, with a solution of a measuredamount of boric acid in 100 grams of methanol. The slurry was stirredfor 5 to 10 minutes or so, and the catalyst solids were separated andtreated as in Example 1. The catalyst was then used to methylate toluenebe reaction of toluene and methanol supplied in about 5:1 mole ratio andcontacting the catalyst at a bed temperature of 410° C. The results arereported in Table 1.

                  Table 1                                                         ______________________________________                                        Toluene Methylation                                                           Cesium zeolite with H.sub.3 BO.sub.3 Added (methanol)                                H.sub.3 BO.sub.3                                                              in solution                                                                             Con-    Selectivity                                          Catalyst                                                                             (grams)   version (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                              ______________________________________                                        A      0         46      46      30    36.5  5.1                              B      1         44      54.4    35    46.8  9.4                              C      2         51      55.0    41    52.0 13.0                              D      3         62      49.0    67    47.3 18.7                              E      4         64      49.4    66    48.6 20.9                              ______________________________________                                    

In the above table, and for other data reported herein, conversion isbased on methanol, and is the percentage of methanol in the reactantstream which has been converted to other compounds. Selectivity (S + EB)is the percentage of methanol converted which is found as styrene andethylbenzene. S₈₀ is the selectivity at 80 conversion of the methanol.Ratio is styrene compared to styrene plus ethylbenzene, on a molepercentage basis. "Coke" is a relative number, indicating the tendencyof the catalyst to form carbon, with higher values indicating morecarbon.

The data indicates that the presence of boron results in improvement inselectivity to styrene and ethylbenzene as well as an increase in theratio of styrene in that product. Conversions are also increased,indicating good activity even at a temperature of only 410° C. Suchconverions are obtainable at gaseous hourly space velocities of 950hr⁻¹, and faster space velocity will generally lower conversions, whileslower space velocities raise conversions. The improved selectivity andtherefore higher yield of styrene was obtained despite the higher carbonformation indicated by the coke index.

The results in the methylation reactions herein are largely reported onthe basis of methanol, as the yields based on toluene are generally veryhigh, while the methanol is the reactant with a tendency to undergo sideor decomposition reactions and with regard to which improvement overpreviously known procedures is sought.

EXAMPLE 3

Catalysts were prepared as in Example 2, but utilizing acetone as thesolvent in the slurrying operation, rather than methanol. The catalystwas then used to methylate toluene with methanol at 950 hr⁻¹ spacevelocity as in Example 2, but at a temperature of 450° C., with resultsas reported in Table 2.

                  Table 2                                                         ______________________________________                                        Toluene Methylation                                                           Cesium zeolite with H.sub.3 BO.sub.3 Added (Acetone)                                 H.sub.3 BO.sub.3                                                              in solution                                                                             Con-    Selectivity                                          Catalyst                                                                             (grams)   version (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                              ______________________________________                                        F      0         99      29.4     8    41.6  7.4                              G      0.5       98      44.9    27    46.9 13.8                              H      1.0       97      46.8    43    48.6 12.5                              I      2.0       92      43.7    76    46.9  7.2                              ______________________________________                                    

The presence of boron again improves selectivity to styrene andethylbenzene, and the ratio of styrene in the product. Also the cokeformation was lower than with some other catalysts. Referringparticularly to catalyst I, the conversion, selectivity and ratio wereall high, resulting in a very good styrene monomer yield, 33% per pass.Acetone has advantage as a solvent for addition of boron or othercomponents subsequent to the zeolite preparation, as it has lesstendency than more polar solvents to cause ion exchange or similarreactions which result in loss of cations.

EXAMPLE 4

Cesium exchanged zeolite X was prepared as in Example 1, but withoutboron additive. Twenty gram portions of the zeolite were used. Theresulting cesium zeolite was then impregnated with a boron compound bytreating the zeolite with approximately an equal weight of methanol,containing one gram of a boron compound. The zeolite was then vacuumdried and activated for catalytic use. Results for reaction of methanoland toluene at 410° C. and under previously described conditions arereported in Table 3.

                  Table 3                                                         ______________________________________                                        Toluene Methylation                                                           Cesium Zeolite with Boron Compound Impregnated                                       Boron     Con-    Selectivity                                          Catalyst                                                                             Compound  version (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                              ______________________________________                                        J      None      67      34.9    17    33.3  6.7                              K      H.sub.3 BO.sub.3                                                                        68      44.6    55    44.8 16.5                              L      B.sub.2 O.sub.3                                                                         60      44.0    80    45.9 16.1                              M      Na.sub.2 B.sub.4 O.sub.7                                                                77      43.3    27    43.3 10.6                              ______________________________________                                    

The various forms of added boron resulted in improved selectivity.

EXAMPLE 5

Catalysts were prepared from type X (Linde SK 20) and type Y (Linde SK40) zeolites, by exchange with cesium hydroxide in water. Additionalcatalysts were prepared under the same conditions, but with phosphoricor boric acid added in the exchange solution, to bring it to a pH of 10.The catalysts were employed in the reaction of methanol and toluene at950 hr⁻¹ gaseous hourly space velocity and 450° C., with resultsreported in Table 4.

                  Table 4                                                         ______________________________________                                        Methylation of Toluene                                                        Cesium Zeolites with Phosphorous or Boron                                     Cat-         Add-    Con-  Selectivity                                        alyst                                                                              Zeolite itive   version                                                                             (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                            ______________________________________                                        N    X       H.sub.3 PO.sub.4                                                                      99    35.2    42    41.4 14.7                            O    Y       H.sub.3 PO.sub.4                                                                      85    26.5    70    --   --                              P    X       H.sub.3 BO.sub.3                                                                      100   44.3    34    46.8 19.9                            Q    Y       H.sub.3 BO.sub.3                                                                      64    37.4    71    37.4 4.1                             R    X       None    100   25.0     1    34.4 6.0                             S    Y       None    93    16.5    13    17.7 3.3                             ______________________________________                                    

Active catalysts are formed from both X and Y type zeolites, and bothphosphorus and boron have a beneficial effect on selectivity of thecatalysts.

EXAMPLE 6

A type X zeolite was treated in an ion exchange procedure to produce acesium exchanged zeolite, and 21.5 grams of the particulate material wasphysically mixed with 1 gram of boric acid. The material was pressedinto disks which were then broken into particulate material andactivated as catalyst by heating in the reactor. At a temperature of410° C., the material was effective for methylation of toluene, givingselectivity of 49.1% to styrene plus ethylbenzene with a 42% ratio ofstyrene, conversion of 69% and a coke index of 10.8.

EXAMPLE 7

Portions of a cesium zeolite catalyst were physically admixed withmeasured amounts of boric acid, to incorporate a specified amount ofboric acid into 21-22 grams or so of zeolite, and the catalysts wereactivated and utilized for methylation of toluene with methanol in amole ratio of 5.25 to 1, 950 hr⁻¹ gaseous hourly space velocity, andtemperature of 410° C. Results are reported in Table 5.

                  Table 5                                                         ______________________________________                                        Methylation of Toluene                                                        Cesium Zeolite - Boric Acid Mixture                                           Weight                                                                        Boric Acid         Selectivity                                                (grams) Conversion (S + EB)  Ratio  S.sub.80                                                                           Coke                                 ______________________________________                                        1       53         52.4      35     50.6 8.9                                  2       37         53.5      44     46.8 5.5                                  5       16         43.1      70     40   1.8                                  ______________________________________                                    

EXAMPLE 8

Procedures are known in which catalysts have been prepared from type Xzeolite by ion exchange to have rubidium or potassium ions. Proceduresas described in Example 1 can be employed. Similar exchanges were run inwhich phosphoric acid had been added to the alkali hydroxide exchangesolution (to pH 10). The catalysts were activated and employed in areaction of toluene and methanol at 5.25/1 mole ratio at 410° C., and950 hr⁻¹ space velocity. Results, along with those for referencecatalysts, are reported in Table 6.

                  Table 6                                                         ______________________________________                                        Toluene Methylation                                                           Catalyst with H.sub.3 PO.sub.4                                                Catalyst        Con-    Selectivity                                           Cation Additive version (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                               ______________________________________                                        Cs     None     61      44.6    27    39.5 8.3                                Cs     H.sub.3 PO.sub.4                                                                       62      44.4    66    41.4 14.7                               Rb     None     61      28.2    24    26.7 7.9                                Rb     H.sub.3 PO.sub.4                                                                       43      42.6    44    32.7 6.6                                K      None     57      21.4    37    21.0 7.6                                K      H.sub.3 PO.sub.4                                                                       45      21.1    60    21.6 6.0                                ______________________________________                                    

The results were fairly good with all of the catalysts, including thosewith potassium and rubidium as cation, and the phosphoric acid improvedthe ratio of styrene in the product.

Rubidium and potassium zeolite catalysts were prepared as in Example 8,from X type zeolite, but with boric acid (to pH 10) in the alkali metalhydroxide exchange solution. The catalysts were employed in the reactionof toluene and methanol (5.25:1 mole ratio in feed) at 410° C. and 950hr⁻¹. Results, along with those of reference catalysts, are reported inTable 7.

                  Table 7                                                         ______________________________________                                        Methylation of Toluene                                                        Catalyst with H.sub.3 BO.sub.3                                                Catalyst        Con-    Selectivity                                           Cation Additive version (S + EB)                                                                              Ratio S.sub.80                                                                           Coke                               ______________________________________                                        Cs     None     61      44.6    27    39.5 8.3                                Cs     H.sub.3 BO.sub.3                                                                       58      51.9    29    49.8 9.2                                Rb     None     61      28.2    24    26.7 7.9                                Rb     H.sub.3 BO.sub.3                                                                       40      40.2    31    36.5 6.0                                K      None     57      21.4    37    21.0 7.6                                K      H.sub.3 BO.sub.3                                                                       44      22.5    62    24.6 7.3                                ______________________________________                                    

The boric acid resulted in improved catalysts, note the improvement inS₈₀ in each case over the reference catalyst.

In the conversion of toluene to styrene and ethylbenzene over thecatalysts of the present invention, reactants other than methanol can beused. Such reactants are for convenience termed "methylating" agentsherein, although styrene does not actually differ from toluene by amethyl group. Methanol and formaldehyde, or various forms or sources offormaldehyde can be used, e.g. trioxane, methylal, paraformaldehyde, orcommercial formaldehyde solutions such as Formcel formaldehyde solution(55% formaldehyde, 10% water and balance methanol).

EXAMPLE 9

A boron-containing catalyst was prepared in accordance with theprocedure of Example 1, but employing a type X zeolite prepared in thelaboratory and very similar to SK 20 zeolite used in Example 1. Thecatalyst was employed under the usual conditions in the reaction ofmethanol and toluene (5.25 moles/1 mole) with results as follows

                  Table 8                                                         ______________________________________                                                               Selectivity                                            Temperature                                                                            Conversion    (S + EB)  Ratio                                        ______________________________________                                        450° C                                                                          98            48.3      10                                           430° C                                                                          85            54.2      18                                           410° C                                                                          60            58.3      24                                           ______________________________________                                    

The effluent sample for the 450° C. readings was taken after the feedwas on stream for ten minutes, the 430° C. sample after an additional17.5 minutes, and the 410° C. sample after an additional 17.5 minutes.

The boron-containing catalyst described above was utilized in a reactionof trioxane with toluene. A feed of 30 moles toluene/1 mole s-trioxane(10/1 mole toluene/CH₂ O) was employed at the usual space velocity andat 400° C. An effluent sample was taken after 17 minutes, and anadditional sample after 37 minutes, with results as follows:

                  Table 9                                                         ______________________________________                                                          Selectivity                                                 Time  Conversion  (S + EB)  Ratio   Coke                                      ______________________________________                                        17 min.                                                                             100         41.9      75      15                                        37 min.                                                                             100         36.5      77      18                                        ______________________________________                                    

The results indicate the boron-containing catalyst was successfully usedfor reacting trioxane and toluene to form styrene and ethylbenzene. Thetrioxane utilized was s-trioxane, m.p. 58°-60° C., mol. wt. 90.08.

After the reaction with trioxane, the coke was burned off the catalystfor 38 minutes (16 millimoles coke) and the catalyst was then utilizedfor reacting toluene and methanol (5.25/1 mole ratio) at 400° C., with asample after 5 minutes showing 49% conversion, 53.5% selectivity, aratio of 43%, and coke 9.8.

In the production of styrene and ethylbenzene according to the presentinvention formaldehyde, or forms or derivatives of formaldehydeproducing formaldehyde in situ can be employed and are contemplated inthe use of formaldehyde described herein. Also it will be recognizedthat various industrial sources of methanol or formaldehyde areavailable, as for example methanol produced in a methanol reformer fromcarbon monoxide and hydrogen obtained in a cracking process.

What is claimed is:
 1. A catalyst comprising a crystallinealuminosilicate zeolite of the faugasite structure with SiO₂ /Al₂ O₃mole ratio in the range of about 2 to about 8 and including potassium,rubidium or cesium cations or combinations thereof, and containing boronor phosphorus or combinations thereof.
 2. The catalyst of claim 1containing boron.
 3. The catalyst of claim 1 in which the zeoliteincludes cesium cation.
 4. The catalyst of claim 3 containing boron. 5.The catalyst of claim 1 in which boron has been introduced by additionof boric acid.
 6. The catalyst of claim 1 in which boron has beenintroduced by addition of an oxide of boron.
 7. The catalyst of claim 1in which potassium, rubidium or cesium cations have been introduced intoa type X or Y zeolite by ion exchange procedures to have at least 50% ofthe potential alkali metal content as such cations.
 8. The catalyst ofclaim 7 in which cesium is at least 60% of the potential alkali metal.9. The catalyst of claim 8 in which the zeolite is type X.
 10. Thecatalyst of claim 8 containing boron.
 11. The catalyst of claim 10 inwhich boron is present in an amount of 0.1% to 2% by weight of thecatalyst.
 12. The catalyst of claim 1 in which boron or phosphorus arepresent in amounts no greater than 5% by weight of the catalyst.